Correlation of Different Signs for Assessment of Dry Eye Syndrome

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Dry eye syndrome (DES) is a highly prevalent ocular condition inducing an inflammatory response of the ocular surface. Common symptoms include ocular discomfort, visual impairment and instability of the tear film with potential damage to the ocular surface.

The rationale of the present study is to compare signs as assessed with new methods such as measurement of tear film thickness, tear film osmolarity and scattering of the tear film with well established methods for assessment of the severity of DES (Break up time, staining of the cornea with fluorescein). Additionally, impression cytology and determination of tear cytokines/chemokines will be performed to obtain information about inflammatory processes on the ocular surface.

Tear film thickness as measured with optical coherence tomography (OCT) [ Time Frame: once on the study day ]

tear film thickness measured in micrometers

Secondary Outcome Measures
:

Visual Acuity [ Time Frame: once on the study day ]

Total number of letters read using ETDRS Charts

Tear film osmolarity [ Time Frame: once on the study day ]

Tear film osmolarity measured in mosmol/l

OSI (Objective Scattering Index) [ Time Frame: once on the study day ]

The objective scattering index will be measured using the OQAS system (Visiometrics, Spain)

Staining of the cornea with fluorescein [ Time Frame: once on the study day ]

The cornea will be divided into 5 regions (central, inferior, nasal, temporal, inferior) and each region will be graded from 0-4 in 0.5 steps as described in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) study.

Impression cytology [ Time Frame: once on the study day ]

After topical anesthesia of the eye, filter material is placed on the conjunctiva to obtain cytological samples, which will be prepared and evaluated.

Tear cytokines/chemokines [ Time Frame: once on the study day ]

Samples of 40 µl tears will be taken with a glass capillary and stored in vials. The concentrations of several cytokines and chemokines will be evaluated.

Subjective symptoms of dry eye syndrome [ Time Frame: once on the study day ]

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